David Einhorn beginning to question his investment strategy

After his Greenlight Capital has gotten walloped by the S&P 500 for years, the hedgie told his investors that he may have been investing via an outdated set of principles.

“What if equity value has nothing to do with current or future profits and instead is derived from a company’s ability to be disruptive, to provide social change, or to advance new beneficial technologies, even when doing so results in current and future economic loss?” Einhorn wrote in a letter to his investors — a copy of which was obtained by The Post.

Misreading market factors led Einhorn recently to short Tesla — one of the strongest performing stocks in recent years.

Tesla is up 58 percent this year despite burning through billions of dollars in cash and posting a loss of $800 million in the six months ended June 30.

Einhorn, a value investor who oversees $7 billion, according to reports, doesn’t see the old rules — centered on profits — returning any time soon. Value investing may no longer be “viable,” he said.

Misreading the trend has left Greenlight up only 3.3 percent through Sept. 30.

The broader S&P 500 is up 14.9 percent this year.

Collectively, short-sellers have lost $3.6 billion on bets against Tesla, according to Ihor Dusaniwsky, head of predictive analytics at financial analytics firm S3 Partners.

Despite recalls and other manufacturing problems Tesla has faced, stock in the Elon Musk-led company has only been minimally impacted — falling just 6 percent in the third quarter
“We believe it deserved to be much worse,” Einhorn wrote.

Nevertheless, Einhorn appears to have only learned his lesson partially in this new climate and shows no sign of giving up his short position.

“Our view is that just because Amazon can disrupt somebody else’s profit stream, it doesn’t mean that Amazon earns that profit stream,” Einhorn wrote, noting that the market doesn’t agree with his take.

Greenlight also had to concede that Neflix — despite facing increased competition and accelerating cash burn — saw its stock rise more than 20 percent in the third quarter.

“Perhaps, there really is a new paradigm for valuing equities and the joke is on us. Time will tell,” Einhorn wrote.